1. Field of the Invention
This invention relates to a method and apparatus for assembling panels into a vehicle component such as a vehicle door, hood or the like using a thermosetting structural adhesive and, more particularly, to a method and apparatus for partially setting the thermosetting structural adhesive to temporarily combine the panels with a strength sufficient to tolerate external forces to be exerted thereon during processes for installing the vehicle component to a vehicle body.
2. Description of the Prior Art
Heretofore, several approaches have been utilized for assembling panels into a vehicle component such as a vehicle door, trunk lid, hood or the like. For example, it is common practice to spot-weld inner and outer panels which have their peripheral areas folded over. However, this requires an additional process to remove the mark left on the panel surface by the electrode used in the spot-welding process for the sake of a good finished appearance. In order to eliminate such a spot-welding process, a method has been proposed to use a thermosetting structural adhesive in assembling the panels into a vehicle component, which includes (1) coating a thermosetting structural adhesive entirely or partially on the peripheral areas of the inner and outer panels, (2) folding the edges of the inner and outer panels together to form a vehicle component such as, for example, a vehicle door, (3) installing the vehicle component to a vehicle body, (4) undercoating it such as by electrode-position coating, (5) drying the coating and simultaneously setting the structural adhesive so as to provide a sufficient strength to the vehicle component by applying heat to the entire vehicle body, and (6) final-coating it. One difficulty with such a conventional method is that since the vehicle component is installed to the vehicle body before the structural adhesive is dried and thus while it is not fully cured, one of the inner and outer panels may get out of position with respect to the other, resulting in deformation of the vehicle component, if the vehicle component is wrenched with a strong force for adjustment of its position relative to the vehicle body during installation of the vehicle component to the vehicle body.
Another method has also been proposed to partially heat the edge flange at which the inner and outer panels are folded together by high frequency electrical indication heating for partially setting the structural adhesive before installation of the vehicle component to the vehicle body. In this method, a coil connected to a source of high frequency current is located on the side of the flange which will not be on the outside of the vehicle so as to produce induced current in the flange area so as to heat it. With such a method, however, all of the thickness of the flange will be heated; that is, such induced current will be produced not only in the folded-over portion of the outer panel but also in the flange of the inner panel and the side of the outer panel remote from the coil, causing formation of an oxide film on the surface of the outer panel exposed to view.